Air Pollution Causes 250,000 Diabetes-Related Deaths

China said to have highest attributable burden of disease due to PM exposure: In recent years, the association of air pollution with diabetes has become a growing topic of concern among experts in the field. The global burden of this association, however, has not been extensively studied and remains relatively uncharted.

Using data published from the Lancet Commission on pollution and health, investigators of a new study sought to examine the relationship between PM, the most most studied air pollutant, and diabetes. While previous studies have linked PM to increased risk of chronic diseases such as kidney disease and cardiovascular disease, few studies have delved deep into the global impact of diabetes with prolonged exposure to PM2-5.

In a July 2018 study published in The Lancet, investigators used data from the U.S. Department of Veteran Affairs’ to build a longitudinal cohort of over 1.7 million U.S. veterans with no prior history of diabetes and linked these patients to the U.S. Environmental Protection Agency’s Community Multiscale Air Quality Modeling System of PM2-5.

The overall aim of the study was to quantify both the national and global burden of diabetes caused by exposure to PM2-5 using the Global Burden of Disease (GBD) methodologies.

Participants of 194 countries and territories included in the study were followed for 8.5 years (median duration) from 2003 to 2012 and were deemed as having developed diabetes if an HbA1c >6.4% was observed, if they were placed on a glucose-lowering medication, or if their diagnosis was defined as diabetes by the International Classification of Diseases-9 code.

Cox proportional hazard models and spline analyses were used to assess the relationship between the risk of diabetes and exposure to PM2-5. National exposure levels of PM2-5 were obtained from GBD 2015 and were derived from the combination of satellite and geographical data, surface measurements, as well as a chemical transport model. GBD 2016 gave investigators data regarding the global burden of diabetes, such as incident rates and disability-adjusted life years.

Investigators first focused on exposure levels of PM2-5 in the ten most populated countries. They found that overall, as the concentration of PM2-5 increased from 5.0µg/m3 up to 12.0µg/m3, so too did the risk of incident diabetes in each country. This attributable risk was seen at concentrations much lower than the concentrations of PM2-5 identified as potentially dangerous by the World Health Organization, which is 10.0µg/m.

While results of the study did in fact show that an increase in PM2-5 was associated with an increased risk of developing diabetes (HR 1.08, 95% CI 1.05–1.12), this study was moreso focused on the impact this association had on a global scale.

Investigators found that the attributable burden of disease (ABD) was over 3 million people globally [3,002,900 ((2,208,600–3,798,900)]. Overall, China was found to have the greatest ABD of 600,300 people. The United States had an ABD of 149,500 people. This study also examined years of life lived with a disability (YLD) and found that the YLD per 100,000 people globally was 57.0 years.

Finally, and the statistic that may hold the greatest weight, investigators of this study estimated that globally in 2016, there were 206,105 deaths from diabetes that could be attributed to PM2-5 exposure (95% UI 153 408–259 119).

While there have been previous studies that have shown the link between air pollution and chronic diseases, such as diabetes, this study was able to show the impact that this association has on peoples’ lives and, more importantly, their deaths.

Although the subject of air pollution association with diabetes may not be at the forefront of medicine, it is an important topic that may one day garner greater attention among environmentalists, scientists, and clinicians alike.

Practice Pearls:

An increase in PM2-5, the most studied air pollutant in modern society, is associated with an increased risk of diabetes even at concentrations below the WHO standard.

Globally, an average of 40.4 people out of every 100,000 could attribute their diabetes to PM2-5 exposure, with China having the highest attributable burden of disease.

In 2016, the number of deaths from diabetes associated with PM exposure was 206,105, globally.